1. Field of the Invention
The present invention relates to an ultra-precision two-dimensional moving apparatus, or more in particular to an ultra-precision two-dimensional moving apparatus suitable for use as a work table for a reduction projection exposure apparatus or an electron-beam exposure system.
2. Description of the Prior Art
The ultra-precision X-Y moving table used for the conventional systems mentioned above requires a positioning accuracy as high as 0.1 .mu.m on the one hand and a high-speed positioning function on the other hand, and it is common practice to use a composite-type moving mechanism including a combination a high-speed X-Y coarse-stage and an X-Y fine-stage.
The conventional composite-type moving mechanism is of a four-stage structure comprising a Y coarse-table moved along a Y axis on an X coarse-table moved along an X axis, and an X fine-table and a Y fine-table mounted on the Y coarse-table. This construction is complicated and high in cost, and also with an increased weight of the moving parts, adversely affects the high-speed positioning.